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1.Gravitational pull of the moon and sun 2.Centripetal force of the rotating Earth Tides are generated by:

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Presentation on theme: "1.Gravitational pull of the moon and sun 2.Centripetal force of the rotating Earth Tides are generated by:"— Presentation transcript:

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2 1.Gravitational pull of the moon and sun 2.Centripetal force of the rotating Earth Tides are generated by:

3 the gravitational pull of the moon and sun - moon has 2x greater gravitational pull than the sun - sun is 10 million x more massive than the moon and is 390 times farther away

4 Centripetal force

5 CENTRIPETAL GRAVITATIONAL FORCE GRAVITATIONAL & CENTRIPETAL

6 Diurnal Tide: 24 hr 50 min cycle Semi Diurnal Tide: 12 hr 25 min cycle Mixed Tide: 12 hr 25 min cycle Tidal Cycles

7 High water: a water level maximum ("high tide") Low water: a water level minimum ("low tide") Tidal range: the difference between high and low tide Spring Tide: full moon and new moon (14.77 days) Neap Tide: 1 st quarter and 3 rd quarter (14.77 days) Description of tides Intertidal zone High tide Low tide

8 The monthly tidal cycle (29½ days) About every 7 days, Earth alternates between: –Spring tide Alignment of Earth-Moon-Sun system (syzygy) Lunar and solar bulges constructively interfere Large tidal range –Neap tide Earth-Moon-Sun system at right angles (quadrature) Lunar and solar bulges destructively interfere Small tidal range

9 Earth-Moon-Sun positions and the monthly tidal cycle Spring Tide Highest high tide and lowest low tide Neap Tide Moderate tidal range

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12 Tidal Patterns Semidiurnal tides- two high and two low per day; Cape Cod, MA (high latitudes) Diurnal tides- one high and one low per day; Mobile, AL (low latitudes) Mixed pattern tides- Two high and two low tides per day BUT with successive high tide levels that are VERY DIFFERENT from each other; Hawaii (mid latitudes) Type of tide depends on: Position on the globe Water depth Contour- shape of ocean basins

13 Location of Tide Types World Map

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15 The Bay of Fundy: Site of the world’s largest tidal range

16 Alma at High Tide Alma at Low Tide Bay of Fundy

17 La Rance tidal power plant at St. Malo, France.

18 Tidal bore = a true tidal wave Wall of water that moves upriver Caused by an incoming high tide Occurs in some low-lying rivers Can be large enough to surf or raft

19 Corals exposed to air at extreme low tide

20 bio/mbweb.html Tidal Information HAWAIIAN ISLANDS Mean Spring Mean Tide Station Latitude Longitude Range Range Level Predictions SAND ISLAND, MIDWAY ISLANDS 28° 12.7' 177° 21.6' PredictionsPredictions Laysan Island 25° 46' 171° 45' PredictionsPredictions East Island, French Frigate Shoals 23° 47' 166° 13' PredictionsPredictions Nonopapa, Niihau Island 21° 52' 160° 14' PredictionsPredictions Kauai Island Waimea Bay 21° 57' 159° 40' PredictionsPredictions Port Allen, Hanapepe Bay 21° 54' 159° 35' PredictionsPredictions NAWILIWILI 21° 57.4' 159° 21.6' PredictionsPredictions Hanamaulu Bay 22° 00' 159° 20' PredictionsPredictions Hanalei Bay 22° 13' 159° 30' PredictionsPredictions Oahu Island Haleiwa, Waialua Bay 21° 36' 158° 07' PredictionsPredictions Waianae 21° 27' 158° 12' PredictionsPredictions HONOLULU 21° 18' 157° 52' PredictionsPredictions Hanauma Bay 21° 17' 157° 42' PredictionsPredictions Waimanalo 21° 20' 157° 42' PredictionsPredictions MOKUOLOE 21° 26.2' 157° 47.6' PredictionsPredictions Waikane, Kaneohe Bay 21° 30' 157° 51' PredictionsPredictions

21 Inquiry 1.Which has the greatest tidal effect– sun or moon? 2.Where is the greatest tidal range located? 3.Which lunar phase produces moderate tides? 4.How is a tidal bore created?


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